1. Field of the Invention
The present invention relates to an apparatus for and method of cleaning a surface, and particularly to an apparatus for and method of removing foreign matter deposited on a semiconductor substrate in the process of manufacturing semiconductor devices.
2. Description of the Related Art
In the process of manufacturing semiconductor devices such as memory devices, foreign matter composed of polymers or the like is sometimes deposited on the surface of a semiconductor substrate. If semiconductor devices are manufactured with such foreign matter deposited on the semiconductor substrate, a problem arises in that the electrical characteristics of the semiconductor device obtained as a product deteriorate. Hence, after foreign matter deposited on a semiconductor substrate is removed, the next process is performed.
For example, the process of manufacturing semiconductor memory includes a process in which a silicon oxide film 2 is formed on a silicon substrate 1, as shown in FIG. 3A. Then the film 2 is subjected to patterning with a photoresist 3, as shown in FIG. 3B, and with this photoresist 3 as a mask, the silicon oxide film 2 is selectively etched, as shown in FIG. 3C. Usually, the silicon oxide film 2 is etched in an etching chamber using CHF.sub.3, CmFn+H.sub.2 or the like as an etching gas. CxFy type polymers are formed in the etching chamber during this etching. These polymers are deposited on the surface of the silicon substrate 1 that is exposed as a result of etching, thereby forming a foreign matter layer 4, as shown in FIG. 3C. If this foreign matter layer 4 is allowed to stay, it will be difficult to manufacture a semiconductor memory device which exhibits excellent electrical characteristics.
For this reason, in the prior art, SF.sub.6, O.sub.2 or the like is used as a reactive gas and plasma etching is performed. After the foreign matter layer 4 accumulated on the silicon substrate 1, as shown in FIG. 3D, is removed, the next process is performed.
However, if plasma etching is performed, since the surface of the silicon substrate 1 is exposed to a plasma, damage may be caused due to the impact of electrons and charged particles such as ions and variations in the potential on the surface. As a result, a problem exists in that the electrical characteristics of manufactured semiconductor devices deteriorate.